SHANGHAI, April 28 (Reuters) - China’s main stock indexes fell on Friday and looked set for their third straight weekly loss on fears that regulators will step up their latest crackdown on riskier types of financing and speculation.

While China’s regulatory enforcement sprees have tended to wax and wane in the past, investors fear there may be no let up in the latest campaign after President Xi Jinping made a rare speech this week on financial stability.

Xi called on Tuesday for increased efforts to ward off systemic risks to help maintain financial security, the official Xinhua news agency said.

“We think it sends an important signal to support the ongoing tightening of financial regulation and enforcement,” Citi wrote in a recent note.

The blue-chip CSI300 index fell 0.7 percent to 3,423.68 points by the midday break, while the Shanghai Composite Index lost 0.3 percent to 3,141.55.

The CSI300 looked set for a loss of 1.2 percent on the week and the SSEC around 1 percent.

Sustained efforts by authorities to encourage or force more deleveraging in the system could tighten liquidity and sour investors’ sentiment further, said Zhang Gang, an analyst with China Central Securities, while adding he did not see further substantial losses.

China watchers have generally expected another modest increase in short-term interest rates by the central bank around June, but see no aggressive tightening moves ahead of a major leadership transition later in the year.

Still, the People’s Bank of China (PBOC) and other regulators have ramped up the pressure on a number of fronts as they look to contain financial risks after years of debt-fueled stimulus.

The PBOC has drained 815 billion yuan ($118.18 billion) on a net basis from money markets via open market operations so far this year, but has still stepped in and injected funds from time to time when markets appeared to be growing too stressed.

“The decline in the second half of April was driven more by soured sentiment, as speculative money suffered setbacks. It could take time for the market to recover,” a South China-based fund manager pointed out.

Main sectors fell across the board on Friday, with losses led by the consumer sector, which posted a 3 percent loss as investors took profits after a strong rally.

Liquor maker Jiangsu Yanghe Brewery dived as much as 10 percent to a 10-week low, poised for its worst day since August, 2015.

In Hong Kong, stocks slipped as investors took profits.

The Hang Seng index fell 0.5 percent to 24,588.27, though still looked set to end the week 2.3 percent higher.

The China Enterprises Index lost 0.3 percent, to 10,234.95. (Reporting by Luoyan Liu and John Ruwitch; Editing by Kim Coghill)